Core bit



May 24y 1938, c. A. DEAN 2,118,397

CORE BIT` Filed March 15, 1937 Tll" Tl 'E' i "JZQ Z r f3 INVENTOR ATTO RN EY Patented May 24, 1938 UNITED STATES PATENT oFI-lcE 7 Claims.

'I'his invention pertains to improvements in earth-boring core drills,and particularly to means for controlling flow of drilling iluid inpassages of the drill head.

Core drills operate in muddy fluid at the bottom of the drill hole. Suchuid is pumped down from the surface through the drill barrel and flowsthrough orifices near the cutters. This tends to clog the variouspassages. For example, the mud at high temperaturea'such as areencountered in .f some of the deep wells, tends to become exceedinglyviscous and even to bake. Moreover, plugging commonly occurs when adrill is lowered into the mud at the bottom. The muddy uid flows fromwithout the drill seeking its own level in the empty drill passages, toa height determined by the prevailing hydraulic pressure. Ordinarilythis mud contains suspended solids of a size sulciently large toV clogthe drill orices or the passages surrounding the inner core barrel.These solids become so irmly wedged under pressure of the fluid flowinginto the drill that frequently despite counter-pressure when the mudpumps are started, some of the passages remain clogged during drilling.

An object of this invention is to provide improved means for avoidingplugging of the iluid passages of a core drill and to assure uniformoperation of the various orifices during drilling. A particular objectis to provide a core drill adapted to keep the space between an innercore barrel and the outer drill barrel free from plugging when the drillis lowered into mud at the bottom of a drill hole. A further object isto divert drilling iluid from the annular space about an inner corebarrel until predetermined pressures are available for iiushing theannular space and its outlet orifices. Yet another object is directed tocore drills of the type having a vertically reciprocable inner corebarrel to actuate core-gripping dogs, such for example as the drillsshown in U. S. Patents No. 1,850,386 or 1,984,867. y Such objects are toprovide means in such drills for positively diverting drilling fluidfrom outsidethe inner core barrel regardless of the position of thebarrel when the drill is in mud at the bottom. These and other objectswill be apparent in the following description of a specific illustrativeembodiment of the principles of this invention.

Reference is made to the accompanying draw ing of a preferred form ofthis invention and to the appended claims which particularly point outnovel features of this invention.

In broad principle, these and other objects are accomplishedadvantageously by providing a drill (Cl. Z55-72) in which are an innercore barrel and a iuid passage outside the core barrel, a valveco-operating therewith for closure of the passage, and a releasablelatch to control the valve. In more specific and preferred form thevalve is held by a shearable pin to close the passage. This valvecontains a relatively large fluid conduit communieating between drillstem and the interior of the core barrel to maintain low pressure on thelatch, and contains a seat for closure of the port so that pressure maybe applied to move the valve to open the passage outside the corebarrel.

In the drawing:

Fig. 1 is a cross-sectional view of a core drill with inner core barreland fluid-diverting valve in non-drilling position, and

Fig. 2 is a cross-sectional view similar to Fig. 1 but with the innerbarrel closed and valve open to divert fluid for drilling.

Referring more particularly to the drawing, a core drill I is showncontaining an inner core barrel 2 in the drill head. In the form shown,though other forms may be used, this barrel is of the verticallyreciprocal type which actuates core gripping dogs. Core barrel 2 issurrounded by annular passage 3 which communicates at the bottom throughjets 4 with the drilling cutters 5. Passage 3 at the top communicateswith a central bore 6 in the drill stem through intermediate ports 1 inthe upper end of the core barrel 2. Passage 3 above ports 'I is closedby resilient rings 8 about the upper end of core barrel 2.

Within the upper end of core barrel 2 a valve sleeve 9 is tted to slidevertically past the ports 1 so as to close ports 1 when the valve is inupper position and to open the ports when in lower position. The valvesleeve is open throughout and iltted snugly to slide between constrictedwalls of the core barrel. Limits for vertical movement of the valvesleeve are established by shoulders I0 and I I on the sleeve to engagecorresponding stops in the walls of the core barrel.

'Ihrough the constricted wall of the core barrel and the contacting sideportion of the valve sleeve are horizontal openings I2 and I2a toregister 45 with each other when the valve sleeve 9 is in upperposition. Thus a pin I3 to serve as a releasable latch may be insertedtherein to lock valve 9 in position to cover ports I and preventdiversion of iluid between annular passage 3 and drill bore 6. 50 Pin I3is inserted before a drill is lowered into a drill hole. 'I'his pin mayconsist of a nail or the like, of size commensurate to shear under thecontemplated pressures when the valve 9 is closed.

Valve sleeve 9 contains an elongate uid pas- 55 sage I4. 'Thispassageway I 4 at its top is provided with a-flaring valve seat I5 toreceive a ball I6 to close conduit I4, against communication of fluidbetween the space within core barrel 2 and bore 6 of the drill stem.

In operation, as a drill is being lowered to the bottom of a drill hole,drilling mud and debris under hydraulic pressure flow into the drill andrise to seek the level of the fluid outside. This fluid containsparticles large enough to jam in the passage surrounding the inner corebarrel orelse to jam in the jets opening near the'cutters. Under theprevailing hydraulic pressure such stoppage of these passages usuallyoccurs in ordinary drills. Moreover under modern conditions of coredrilling at great depths in the earth the adverse factor of hightemperature tends to bake or gel the mud that rises through the cutterjets. Consequently with ordinary drills when the pressure is reversedfor drilling and even though pump pressure is applied, the drilluidflows out unevenly and the action and wear of the cutters is irregular.

However, whensa drill embodying the present invention is lowered into abore hole, annular passage 3 is closed at the upper ports 1, and thehydraulic pressure on the mud at the bottom of the drill is relievedthrough the opening I4 in the top of the core barrel. 'I'he relativelylarge crosssection of the core barrel facilitates ow of the mud thereineven though solid particles of considerable size be present. But flow inthe annular passage 3 is substantially avoided, for with outlet at portsI closed, back pressure of the entrapped air and the relativeconstriction of passage 3 divert the mud unto core barrel 2. Air in corebarrel 2 escapes freely through passage I4.

When this improved drill reaches bottom and. is ready for drilling,pumps are started in customary manner to force drilling fluid downthrough the drill stem. At first the fluid may flow out through corebarrel 2. Then ball closure I5 is dropped with the fluid through thestem and seats itself in valve sleeve 9, closing opening I 4. Thuspressure of the pumps and drilling mud is exerted on valve 9 so thatfinally the sleeve is forced down to release the latch, or shear thelatch pin I3, as shown in Fig. 2. Thus ports I are opened so that withthe predominant pressure downward and with annular passage 3 clear,drilling mud from the pumps readily flows uniformly through the cutterorifices for drilling.

While in accordance with the patent statutes a particular embodiment ofthis invention has been described for illustration of the principlesthereof, and the best mode of application now contemplated, it isevident that variations and other specific arrangements are contemplatedand various adaptations of this invention may be made by those skiued inthis art, within the scope of the appended claims.

What is claimed is:

1. A core drill comprising a bit head .adapted t0 be attached to ahollow drill stem, a core barrel therein and a fluid passage around thecore barrel, either the core barrel or the fluid passage being open forflow of fluid between the drillA stem and the bottom cutters of the bit,means initially to close the fluid passage and to divert fluid throughthe core barrel, and means to close the core barrel and to divert fluidthrough the fluid passage to the cutters.

2. A core drill comprising a'bit head adapted to be attached to a hollowdrill stem, a core barrel vertically movable therein and initially openat the top for ilow of drilling fluid therethrough, and a fluid passageoutside the core -barrel communicating between the drill stem and thebottom cutters of the drill, said passage initially being closed at itstop, and valve means to close the core barrel at any vertical positionand to open the passage for diverting flow of uid to the bottom cuttersfor drilling.

3. A core drill comprising a bit head adapted to be attached to a hollowdrill stem and containing a core barrel and a fluid passageoutside thecore barrel communicating between the drill stem and the bottom cuttersof the drill, closure means for the passage around the upper portion ofthe core barrel, ports in the core barrel initially affording fluidcommunication between the portions of the passage above and below theclosure, a valve to close said ports and means to open said valve andports for fluid to ow to the cutters through the passage outside thecore barrel.

4. An earth drill comprising a head adapted for attachment to a hollowdrill stem, a core barrel therein, a fluid passage outside the corebarrel open at the bottom and closed near the top of the core barrel,ports in the upper part of the barrel to open between the passage andthe drill stem, a valve at .the upper part of the core barrel to closethe ports, said valve containing a. fluid conduit communicating betweenthe drill stem and the interior of the core barrel, and a seat in saidvalve to receive a closure element foi the conduit, said valve beingadapted to move relatively to the core barrel to open .the ports whenthe closure element is seated in the valve.

5. A core drill comprising a bit head adapted to be attached to a hollowdrill stem, a core barrel therein open at the top, a fluid passageoutside the core barrel and closed near the top of the core barrel,ports between the passage and the core barrel opening, a sleeve flttingin the core barrel opening and movable to open or to close the ports,and means to close the sleeve and core barrel opening and move thesleeve to open the ports and divert fluid through the passage outsidethe core barrel.

6. A core drill comprising a bit head adapted to be attached to a hollowdrill stem, a core barrel open at the top and mounted in the bit head tomove longitudinally thereof, a fluid passage outside the core barrreland closed near the top of the core barrell ports between the passageand the core barrel opening, va sleeve fitting in the core barrelopening adapted to afford fluid communication between the drill stem andthe core barrel and adapted to move to open or to close the ports, and aseat to receive a closure element for the sleeve, whereby under fluidpressure the closed sleeve is adapted to move to open the ports anddivert fluid through the passage outside the barrel.

` 7. A core drill comprising a bit head adapted to be attached to ahollow drill stem, a core barrel therein open at the top, a fluidpassage outside the core barrel, and closed near the top of the corebarrel, ports between the passage and the core barrel opening, a sleevefitting in the core barrel opening andmovable to open or to close theports, and means holding the sleeve to close the ports when the sleeveis open andy releasable on closing the sleeve, and means to close thesleeve and core barrel opening and move the sleeve to open the ports anddivert fluid through the passage outside the core barrel.

CHARLES A. DEAN.

